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STAR-CD
has recently been used by the CSIR (Council for Scientific
and Industrial Research) to analyze the airflow on
the main floor of a casino complex to determine the
distribution of cigarette smoke particles.
Strict laws aimed at curbing smoking
in public venues have recently been promulgated in
South Africa. Many businesses had to make significant
structural changes to their buildings in order to comply
with the new laws, which generally require that designated
smoking areas be completely separated from non-smoking
areas by means of full height partitions.
The STAR-CD model of the main floor
of the casino complex enabled ventilation engineers
to investigate the possibility of confining smoke to
certain areas with effective ventilation and partial
partitions instead of full height partitions which
would harm the aesthetical appeal of the venue.
The engineers were also interested
in the effectiveness of the ventilation system in removing
smoke from smoking areas in the event that they had
to be separated with full height partitions. The STAR-CD
model was therefore adapted to accommodate such a scenario
as well.
The grid presented a modeling challenge
due to the many geometric details that had to be captured.
The ability of PROSTAR to generate three-dimensional
cells by extruding two-dimensional shell cells came
in very handy. A floor plan detailing the position
of the machines was used to generate a similar picture
in PROSTAR consisting of shell cells, via the PATCH
command. These cells were then extruded in the vertical
direction to form solid cells to represent four different
types of machines as well as fluid cells representing
the airspace (see figure 1).
The roof detail was also complex,
but had a repetitive pattern and the relevant commands
in PROSTAR made it possible to generate the complete
set of shell cells from one segment. Due to the difference
between the roof and floor detail, the two sections
were joined by means of an arbitrary coupled interface,
situated approximately 4 meters from the floor level.
If the two sections could not be joined in this way,
it would have been virtually impossible to generate
the grid with hexahedral cells alone, and grid development
would have taken far longer.
The remaining part of the grid consists
of the passage surrounding the main floor and includes
several domes. This part of the model was generated
using blocks and is shown in figure 2. Figure 2 also
shows the location of some of the boundaries, which
were automatically applied by running a script of PROSTAR
commands.
The final grid consisted ofapproximately
800 000 fluid cells and was used to perform several
runs, each with different boundary conditions, representing
different ventilation designs. Figure 3 shows one of
these solutions and indicates the expected path that
smoke particles will take when released by smokers
at selected machines.
The model predicted that it would
be difficult to contain the cigarette smoke to certain
areas without significant changes to the ventilation
system. A combination of a modified ventilation system
and partitions around the centre section of the main
floor was found that made it possible to contain and
effectively ventilate the cigarette smoke from that
area.
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